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(No Model.) '2 Sheets-Sheet 1. S. DARLING.

CENTER SQUARE. No. 371,740. Patented Oct. 1.8, 1887.

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SAMUEL DARLING, OF PROVIDENCE, RHODE ISLAND.

CENTER=SQ.UARE.

SPECIFICATION forming part: of Letters Patent No. 371,740, dated October 18, 1.887.-

ApplieationliledJulylQ,1886. Serial No.208.431. (N0 model.)-

To all whom it may concern.- Be it known that I, SAMUEL DARLING, of Providence, in the county of Providence and State of Rhode Island, have invented certain new and useful Improvements in Center- Squares; and I do hereby declare that the foland exact description of the invention, .which will enable others skilled in the art to which it appertains tomake and use the same, reference being had to the aceompanying drawings, and to letter of refer ence marked thereon, which form a part of this specification.

The purpose of this invention is to make a square or instrument that will serve as a universal or center square, a try-square for testing internal and external angles, a bevel, bevel-protraetor, an adjustable try-square, and depth-gage; and it consists, mainly, in making a center-square with a stock having two arms forming a suitable angle, one of the arms having two working-faces, the inner face for the center-square and the outer face for the try-square; an adjustable radial blade, and a revoluble plate or blade-carrier attached to the stock, preferably by a central pivot or shaft, at one side of the center of the angle formed by its two arms, the oifice of said plate being to hold and carry the blade, and also in special details of construction and arrangements, hereinafter described and illustrated.

In the accompanying drawings, Figure 1 is a top view of the head or stock detached; Fig. 2, a top view of my center-square complete; Fig. 3, edge view from 0,- Fig. I, end View from 0". Fig. 5 shows the revoluble blade as arranged to form, with one edge of the stock, the internal angle of a try-square. Fig. 6 shows the same when arranged to form the external angle of a try-square.

The letter A. represents the stock or head of my improved square; B 0, arms, forming, preferably, a right angle; D, base or support for the revoluble plate or disk; E, ear or projection to hold a stop for the blade; F, adjustable radial blade; H, beveled groovein the side of the blade; I, revoluble plate or blade-carrier; J, circle graduatedinto degrees; K, bevel on blade-carrier; L, indexline; M, a hardened-steel stop for the edge of the blade to bear against when the instrument is used as a center-square; N stop for the blade shown in dotted lines F and in full lines in Fig. 6 when it is used as a try-square for testing internal angles, or as shown in Fig. 5, for external angles; 0 P, thumb-nut and pivoted screw-bolt for clamping the bladecarrier and blade. to the stock; Q, rib in the cut-away part of the revoluble plate or blade-carrier I to guide and hold the blade in position.

The opposite side of the stop M (M) serves as a stop for the edge of the blade to bear against when the instrument is used as a trysquare for testing external angles, as shown in dotted lines F. The groove in the side'of the blade may fit the rib tightly and the blade be guided wholly by it; or the groove in the blade and the rib maybe so made that the rib will force the edge of the blade against the'shoulder s by the wedging action of the beveled sides of the rib and groove in the blade S when drawn together by the thumbnut 0 and screw P. Then the instrument is adjusted for a center-square, the index-line should stand at 45 of the graduated circle. When adjusted for a try-square for testing angles, the index should, stand at 90..

In my application No. 194 365, filed March 8, 1886, I have claimed an adjustable trysquare having a cutaway portion or recess and an adjustable blade one edge of which is forced and held against the shoulder in the recess by means of a clamp and the wedging of opposite bevelsurlaces, and also an adjustable try-square having a blade-holding stock or carrier provided with a cut-away portion or recess having a groove with a beveled side, and a blade provided with a longi tudinal rib adapted to fit the groove in the cutaway portion or recess, and means for clamping the rib of the blade in the said groove. I therefore make no claim to the same in this application.

Vhat I claim, and Patent, is

A square provided with a stock having an interior angle between two limbs, and having a revoluble and adjustable blade oneedge of which is adapted to bisect the interior angle of the stock, and thus form the center-square, and also upon partial edgwise revolution upon its pivot and endwise adjustment will serve to form both the interior and exterior angles of a try-square with an exterior straight edge of one of the limbs of the center-square, substantially as described.

wish to secure by Letters SAML. DARLING. Witnesses:

PENNINGTON HALSTED,

CHARLES F. BUTTERWORTH.

ICO 

